1. Technical Field
The embodiments described herein relate to a semiconductor device, and more particularly, to a circuit for preventing inflow of high current from an input/output pad by static electricity, and a semiconductor device using thereof.
2. Related Art
Most semiconductor integrated circuit (IC) devices have a circuit for discharging static electricity between input/output pads and an internal circuit in order to protect the internal circuit from damage by static electricity. Protective resistance may also be implemented between the input/output pads and the internal circuit in order to prevent instant inflow of high current by static electricity.
FIG. 1 is a schematic lay-out diagram of a conventional device having and input/output pad and input terminal. In FIG. 1, an electrostatic discharge circuit 5 includes an input/output pad 10, a protective resistance disposed between the input/output pad 10, and an internal circuit 20, which can include an input buffer. The protective resistance includes a plurality of conductive lines 13 disposed between a wire 12 connected to the input/output pad 10 and a wire 14 connected to the internal circuit 20, wherein the conductive lines 13 are made of polysilicon material. The conductive lines 13 form electrical connections with the wire 12 and the wire 14, and intersected on the respective end portions through contacts 12b and 14b of both ends of the wires 12 and 14, respectively.
The semiconductor device has metal lines formed on the lower layer of the input/output pad 10, in order to buffer physical damage of the input/output pad 10 that may occur during a package bonding process. An interlayer insulating film (not shown) for electrical insulation is generally formed between the metal lines 11 and the input/output pad 10.
The metal lines 11 are for preventing a phenomenon that the input/output pad 10 is stripped due to bonding on the upper portion of the input/output pad 10 during the package bonding process. More specifically, the upper portion of the input/output pad 10 is pressed in a predetermined direction during the bonding step to receive force pulled into the upper portion thereof, as the pressure by the material bonding on the upper portion of the input/output pad 10 is removed. At this time, the input/output pad 10 may be stripped due to the force pulled into the upper portion thereof and the metal lines 11 are used as buffer for preventing the stripping phenomenon described above.
In FIG. 1, the semiconductor device can prevent the occurrence of static electricity by the electrostatic discharge circuit and prevent inflow of high current due to static electricity via the protective resistance including the conductive lines 13. However, the semiconductor device of FIG. 1 requires additional space for forming the protective resistance, wherein the protective resistance has to be applied to all input/output pads. Accordingly, the semiconductor device takes up considerable portions of the entire area of the IC, thereby reducing the size of other semiconductor device disposed on the IC.